Method of forming a heating unit



y 7, 1965 c. w. GILLESPIE ETAL 3,

METHOD OF FORMING A HEATING UNIT Original Filed April 12. 1961 F I g. 6

INVENTORS Charles W. Gillespie By Ronald L. Leonard Af orney United States Patent METHGD GF FGRMING A HEATING UNIT Charles W. Gillespie, Vandalia, and Ronald L. Leonard,

Dayton, {)hio, assignors to General Motors Corporation, Detroit, Mich, a corporation of Delaware Griginal application Apr. 12, 1961, Ser. No. 102,499.

Divided and this application Dec. 30, 1963, Ser. No.

1 Claim. (Cl. 29-45565) This invention relates to a domestic appliance and more particularly to an improved electrical connector assembly for connecting the top surface heating unit of an electric range with a power supply. This i a division of Serial No. 102,499, filed April 12, 1961.

In the prior art heating units to which this invention applies, the coiled tubular sheath is formed with a relatively straight terminal portion which extends below the top surface of the electric range for connection with a source of power. To this terminal portion may be connected a terminal block for housing the electrical spade connectors which are selectively electrically engaged through a mating connector lock in electrical supply relationship with the power source. The prior art arrangement is shown more particularly in the patent to Bremer 2,835,780, issued May 20, 1958. In this earlier version, a plurality of subsequent assembly operations are required to attach the various electrical supply components to the tubular sheath. This is not only time consuming and costly, but requires additional components which are eliminated by the teachings of this invention.

Accordingly, it is an object of this invention to provide a terminal block as an integral part of the heating unit.

A more particular object of this invention is the pro vision of a terminal block which is retained in sealed relationship on the tubular heating unit by the terminal connector tabs.

A general object of this invention is the provision of a terminal block which serves as a process fitting for the assembly of a heating unit.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred embodiments of the present invention are clearly shown.

In the drawings:

FIGURE 1 is a fragmentary top elevational view of an electric range provided with a top surface cooking or heating unit suitable for use with this invention;

FEGURE 2 is a fragmentary side elevational View of the heating unit, partly in section;

FIGURE 3 is a partly exploded side sectional view of this invention;

FIGURE 4 is an elevational view taken along line 44 in FIGURE 3;

FIGURE 5 is a side sectional view of the terminal block of this invention;

FTGURE 6 is an elevational view taken along line 66 in FIGURE 5;

FIGURE 7 is an elevational view taken along line 7-7 in FIGURE 5;

FIGURE 8 is an elevational View of a sealing member used in this invention; and

FIGURE 9 is a top elevational view of a connector tab suitable for use with this invention.

In accordance with this invention and with reference to FIGURE 1, an electric range 10 is provided with a range top 12 having a trimmed opening 14 therein for receiving a spirally formed tubular sheath top surface heating or cooking unit 16. A terminal portion 13 of the heating unit is substantially straight and downwardly bent to drop below the top 12 of the range as seen in FIGURE 2. This terminal portion 18 of the heating unit 16 is adapted for pivotally attaching the unit to the range top as well as for electrically connecting the heating unit to a source of power.

The heating unit 16 may be selectively pivotally attached to the underside of the range top 12 as at 20 by a pivot bracket shown generally at 22. The bracket 22 serves to position the heating unit 16 in either a flat horizontal operating position as shown in FIGURE 2 or in a raised position for cleaning. Further details pertaining to the pivot support bracket 22 may be seen in the patent to Bremer 2,948,801, issued August 9, 1960.

To the straight terminal portion 18 of the heating unit 16 may be attached an insulating terminal block 24 which mates in electrical supply relationship with a plug-in cooking unit connector block or insulator 26. The connector 26 is, in turn, electrically connected to an electrical power supply as evidenced by the power supply leads 28.

Turnin now to FIGURE 3 the construction of the integrally assembled terminal block of this invention will be explained more fully. The straight portion 18 of the heating unit 16 is formed with a cylindrical end portion 39 defined by an annular groove 32 spaced from the end of the heating unit. The straight portion 18 forms a tubular sheath to which a pair of heating coils or resistance elements 34, 36 extend. To the coiled resistance or heating element 34 is attached a generally straight electrical conductor portion or terminal wire 33 and to the coil 36 a terminal wire 40. The ends of the terminal wires 33 and 40, it will be noted, extend outside the sheath beyond the end of the cylindrical portion 30. A ceramic insulator or terminal alignment bushing 42 seats within the cylindrical end portion against the annular rib 32 and includes a pair of openings which receive the terminals 38 and 40 and serve to center them within the tubular sheath 18 in permanently fixed and spaced relationship thereto. The terminal block 24 is formed with a pocket 56 which fits over the exposed ends of the terminals 33 and 4t} and sandwiches a resilient gasket or sealing member 43 of silastic or other suitable material between the end of the cylindrical portion 30 and the terminal block 24. Lastly, a pair of electrical spades or connector tabs 44, 46 are fastened to the ends of the terminals 38 and 40. More particularly, the connector tab 44 includes a welding boss such as 45 which is fastened as by welding to the end of the terminal wire 38, whereas the connector tab 46 is fastened as by welding to the terminal wire 40. Thus, when the power supply connector block 26 is plugged into the terminal block 24, the connector tabs 44 and 46 are engaged to condition the heating unit 16 for selective energization.

With reference to FIGURES 5, 6 and 7, the novel terminal block of this invention is shown to be generally drum-like in shape. At one end is formed a cylindrical pocket or recess 51) for receiving the cylindrical end 30 of the tubular sheath. At the opposite end is formed a connector block recess 52. Interconnecting the recesses and 52 are terminal ports 54 and 56 through an interconnecting wall portion of the terminal block 24. At the end of the terminal ports 54 and 56 adjacent the socket 52 are enlarged or flared sections or welding recesses 58 and 60, the purpose of which will be explained hereinafter. The terminal block 24 may be formed of black Bakelite or other suitable insulator material which may be readily molded or formed to the desired configuration.

The following method steps may be used to assemble the foregoing components into a finished spirally formed top surface heating unit. The assembly operation starts by joining each resistance coil to its respective terminal wire. After the coils and terminal wires are fastened together, a ported ceramic insulator 42 is slipped over the (3 ends of the terminal wires to hold the terminals in properly spaced relationship.

Next, the gasket 43 is slipped over the ends of the terminals 33 and 4ti-openings, such as 7%, being provided in the gasket for this purpose. The terminals are then slidably placed through their respective openings 54, 55 in the terminal connector 24. The electrical spades 44 and 46 are fastened respectively as by Welding to the ends of the terminal wires 38 and 4%. Any suitable jig may be used to position properly the spades on the terminal wires during the welding process.

Then, the assembly including the terminal block 24, the electrical spades 44, 46, the sealing member 43 and the combined coil and terminal units are positioned adjacent the unformed straight hollow sheath 1%. The coil and terminal units are threaded through the hollow sheath until the cylindrical end portion 30 of the sheath nests snugly within the socket 50 of the terminal block 2 4 and presses against the sealing member 43 to form a positive seal against spillage.

After the assembly, the unforrned sheath 18 is held in a vertical position-the terminal connector end lowermostand filled with a dielectric material, such as mag nesium oxide 51. At the same time the dielectric material is compacted as by vibration and the top end closed such as at 72.

As a last step, the filled and compacted heating unit assembly is formed into a spiral configuration, such as seen in FIGURE 1. The completed heating unit to may then be fastened to the range top 12 as by the pivot connector bracket 22 so that the terminal block 24 is in position for receiving the male terminal block 26. For further details pertaining to the connector block 26, reference may be had to the aforementioned Bremer Patent 2,835,780.

It should now be seen that an improved top surface cooking or heating unit has been provided wherein assembly operations thereof are greatly simplified and components eliminated to provide a more efficient manufacturing process and a less expensive product. No auxiliary fastening means are required to retain the terminal block to the tubular sheath-the electrical spades serving this purpose by their connection to the terminal wires.

While the embodiments of the present invention as herein disclosed, constitute preferred forms, it is to be understood that other forms might be adopted.

What is claimed is as follows:

The method of forming a heating unit having a dielectric material-filled tubular sheath, first and second resistance coils, first and second terminal Wires, an alignment bushing having first and second holes, a ported sealing ember, first and second connector tabs and a terminal block having first and second ports and first and second recesses connected respectively to the first and second ports thereof, said method comprising the sequential steps of joining said first and second resistance coils respectively to said first and second terminal wires, threading said alignment bushing onto said first and second terminal wires respectively through the first and second hoies thereof to space said terminal wires apart, sliding said first and second terminal Wires through the ported sealing member and respectively through the first and second ports in said terminal block until the ends thereof extend respectively beyond said first and second recesses, welding said first and second connector tabs respectively to said first and second terminal wires, positioning said first and second connector tabs respectively in keyed relationship to said first and second recesses whereby to lock said terminal wires against rotating relative to said terminal block thereby to group said resistance coils, said terminal wires, said alignment bushing, said sealing member, said terminal block and said connector tabs into an assembly wherein said terminal block serves as a process fitting for subsequent method steps before becoming a permanent part of said heating unit, then threading said resistance coils, said alignment bushing and said terminal wires into said tubular sheath until the end of said tubular sheath abuts said sealing member to sandwich said terminal block and said sealing member between said connector tabs and said tubular sheath, said threading being in a manner to space said resistance coils from each other along their lengths and from said tubular sheath, filling said tubular sheath compactingly with said dielectric material to retain said resistance coil in said sheath, closing the end of said tubular sheath through which said dielectric material was filled, and forming said tubular sheath into a heating element of desired configuration.

References Cited by the Examiner UNTTED STATES PATENTS Re. 23,679 7/53 Charbonneau et al. 29l55.69 X

1,754,003 4/ 30 Johnson-Vea et al. 2,643,317 6/53 Tuttle 29-l55.63 X 2,673,335 3/54 Verdon 339275 X FOREIGN PATENTS 131,233 2/49 Australia.

WHITMORE A. WILTZ, Primary Examiner.

JOHN F. CAMPBELL, Examiner. 

